This invention relates to cargo air bags and, more particularly, to an improved construction of a cargo air bag providing improved strength, stiffness, ease of use and economies of manufacture.
It is known in the art to use inflatable air bags as bracing to reduce damaged product, materials, labor and loading time in shipping cargo. Such bags are typically comprised of a plastic inflatable bladder which is surrounded by a multi-walled paper bag to protect the bladder from puncture. An inflation valve extends through the air bag and into the bladder such that the bladder may be filled and expanded with compressed air. The size of the multi-walled bag is such that it expands under the internal pressure of the gas. Such bags are manufactured in a variety of sizes to fill virtually any load pattern and void size and shape in the shipping of products.
In use, product to be shipped, for example, via railcar, trailer or overseas container, is placed in the container. Typically, the load does not fill the container completely and adjacent loads may be spaced from each other or spaced from the ends and side walls of the container. Without bracing of the load, the load would be subject to movement during shipping. The use of air bags prevents lengthwise and/or crosswise movement of such cargo so that the construction of bulkheads is not necessary. In use, an air bag is placed in the void between spaced pallets or load units or between the side or end walls of the container and the load. Thereafter, an operator inflates the bag with compressed air, the bladder and bag expanding to thereby fill the void and brace the load. To remove the load, it is only necessary to simply puncture the air bag so that it can deflate and remove it from the container. Air bags thus provide a fast and easy way to brace a load for shipment.
Today, air bags are typically manufactured by taking a length of multiple-layered paper, folding it on itself at its edges to form an overlapping seam generally along the centerline and then gluing the overlapping edges together. There is thus formed a multi-walled paper tube having open ends. The inflatable plastic bladder is then inserted in the tube by holding the tube up at both ends to expand it and sliding the bladder into the expanded tube. The ends of the bag are then closed and sealed to form the completed air bag.
The construction of these air bags is relatively labor intensive, it being difficult to insert the bladder in the bag in the manufacturing process. Further, this operation of inserting the bladder in the paper tube typically has to be carried out by hand. Still further, in construction of multi-walled air bags of this type, it is necessary to fold the paper on itself which weakens the paper fibers along the folded edges. Experience has shown that if there is a blowout of the bag because of the air pressure in the bag, the blowout typically occurs at the folded edge of the bag where the fibers have been weakened. Further, such air bags typically do not have vertical stiffness. Thus, when placed between the load by the operator, the paper bag tends to sag toward the floor, and the operator must attempt to hold the bag upright while at the same time inflate it. This can be an awkward operation.